I need help with joining these two tables:

Table1

idx idy
---------
one 1
two 2
tree 3


Table2

idy u
-------
1 a
2 b
3 c
4 d
5 e
6 f

I want to show rows from the Table1 that have idx=one joined with all the rows from Table2.
So, I want to join these two tables so that Table1.idy=Table2.idy and Table1.idx=one
The result table should look like this.

Result table:

idx idy u
--------------
one 1 a
NULL 2 b
NULL 3 c
NULL 4 d
NULL 5 e
NULL 6 f

Could someone help me with this?
Thanks.
Rebeka